Hypocrisy in the NFL?

On Sunday I saw a touchdown (TD) celebration that broke the rules. A player scored a TD, quickly went to one knee and said a 3 second prayer. He then got up and quickly jogged to his bench (while high-fiving his teammates) yet he was flagged for excessive celebration because of the drop to one knee. However, in that same game whenever a defensive player made a tackle or a sack, they ran 10 yards down the field in exuberant elation! Were they flagged at all? No.

I'm not arguing that the celebration rule is wrong (although I think it should be changed, but that is neither here nor there). I just don't know how on simple plays where players are paid to make those plays, and afterwards players do some flamboyant act, there is no penalty for excessive celebration but on a TD where a player is quiet and quickly acts in humility he gets flagged for excessive celebration.

Go figure...